Go Figure!

RSS Pre-Conference Workshop 2023

Zak Varty

More Than A Pretty Picture

Visualisation is a key skill in your data science tool kit:

  • Rapidly explore data sets
  • Model evaluation and diagnostics
  • Sharing evidence
  • Telling compelling stories.

Reflective exercise, not a tutorial or rulebook.

Warming stripes graphic on the cover of “The Climate Book”

1: Think About Your Tools

Data visualisation tools

Coffee consumption, visualised. Jaime Serra Palou.

Selecting your tools: Analogue or Digital

Caffeination vs sleep, shown in lego. Elsie Lee-Robbins

Staying in the tidyverse: {ggplot2}


Layered creation of graphics from tidy data.

Learning {ggplot2}:


2: Think About Your Medium

Where will your plot go?

Use cases: exploratory analysis, presentation, report / paper, data journalism.

Considerations:

  • Time investment vs quality
  • Image size / format
  • Time spent with graphic

File types

  • Bitmap Graphics: png, jpeg, gif
    • made of pixels
    • smaller file size
  • Vector Graphics: pdf, eps, svg
    • made of vectors
    • larger file size

3: Think About Your Audience

Know your audience

Who is the intended audience for your visualisation?

What knowledge do they bring with them?

What assumptions and biases do they hold?


Creating personas for distinct user groups can be helpful.

Preattentive Attributes

First impressions count

Issues with scales, area and perspective

Visual perception


Default colour scales


Desaturated colour scales

Alt text, titles and captions

Captions

Describes a figure or table so that it may be identified in a list of figures and (where appropriate).

Alternative text

Describes the content of an image for a person who cannot view it. (Guide to writing alt-text)

Titles

Give additional context or identify key findings. Active titles are preferable.

Graph to show how X varies with Y

Adding Alt-Text to Images

HTML

<img src="path/to/image.png" alt="Alt text goes here.">


pdf (LaTeX)

\usepackage[tagged, highstructure]{accessibility}
\begin{figure}
    \centering
    \includegraphics[]{path/to/image.png}
    \alt{Alt text goes here.}
    \caption{Caption goes here.}
    \label{fig:alt-text-example}
\end{figure}

Adding Alt-Text to Images

Markdown

Great for multi-output documents but many flavours.

Github / Jupyter:

![Alt text goes here.](path/to/image.png)

Quarto:

![Caption goes here](path/to/image.png){alt="Alt text goes here"}

Adding Alt-Text to Plots

When using literate programming alt-text can be added as code block meta-data.


In Quarto:

```{r make-dino-plot}
#| fig-cap: The Datasaurus from the Dino-Dozen.
#| fig-alt: Scatterplot in which the points form the outline of a T-Rex.
#| output-location: slide
par(bg = NA)
plot(x = dino_x,y = dino_y, pch = 16, asp = 1)
```

Adding Alt-Text to Plots

Scatterplot in which the points form the outline of a T-Rex.

The Datasaurus from the Dino-Dozen.

4: Think About Your Story

Data visualisation as storytelling


  • Where does your purpose fall on this triangle?

  • No such thing as neutral presentation.

  • Start with a hook.

5: Think About Your Guidelines

Standardise and document it


Decisions cost time, energy and money. (DRY)


Consider your design choices carefully and write down your decisions and reasoning. (DRY)


This will form the basis of your own style-guide for data visualisation.

Style guides for data visualisation

A Worked example

  • Quarto, R and {ggplot}.

  • Blog post: women in politics.

  • General audience, familiar with UK politics.

  • Representation of women in parliament is improving over time.

  • Style guidelines of blog and political parties.

Out of the Box: A First Attempt

line plot of the number of seats won by women in UK general elections, 1920-2020. Counts are shown for Conservative, Labour, Liberal Democrat and Other parties. Default styles from ggplot2 have been used.

Applying Blog Styling

line plot of the number of seats won by women in UK general elections, 1920-2020. Counts are shown for Conservative, Labour, Liberal Democrat and Other parties. A blog's style guide has been applied.

Fix Confusing Colours

line plot of the number of seats won by women in UK general elections, 1920-2020. Counts for Conservative, Labour, Liberal Democrat and Other parties shown in conventional party colours.

Highlight important takeaway

line plot of the number of seats won by women in UK general elections, 1920-2020. Labour seats are shown in red and all other parties in greyscale to direct attention to the labour results.

Wrapping up

  • Think about your tools

  • Think about your medium

  • Think about your audience

  • Think about your story

  • Think about your guidelines

Image Credits

Further Resources

RSS Best Practices for Data Visualisation

How to make data outputs more readable, accessible, and impactful.

11:40-13:00 Tuesday, 5 September, 2023, Auditorium

Activity!

Exercise 1: Text to Plot

Split into 5 groups and spread around the room.

Try to draw the plot based on the alt-text provided.

08:00

Exercise 2: Plot to Text


Now for the inverse problem:


Write your own alt-text based on the plot provided.

08:00

Exercise 3: Text to plot


Put your alt-text to the test:


Pass your alt-text to another group. They have to try and recreate your plot!

08:00

Build Information

R version 4.2.2 (2022-10-31)

Platform: x86_64-apple-darwin17.0 (64-bit)

locale: en_US.UTF-8||en_US.UTF-8||en_US.UTF-8||C||en_US.UTF-8||en_US.UTF-8

attached base packages: stats, graphics, grDevices, utils, datasets, methods and base

other attached packages: dplyr(v.1.1.2), ggplot2(v.3.4.0) and datasauRus(v.0.1.6)

loaded via a namespace (and not attached): Rcpp(v.1.0.9), cellranger(v.1.1.0), compiler(v.4.2.2), pillar(v.1.9.0), sysfonts(v.0.8.8), tools(v.4.2.2), digest(v.0.6.31), jsonlite(v.1.8.4), evaluate(v.0.20), lifecycle(v.1.0.3), tibble(v.3.2.1), gtable(v.0.3.1), pkgconfig(v.2.0.3), png(v.0.1-7), rlang(v.1.1.0), cli(v.3.6.0), rstudioapi(v.0.14), yaml(v.2.3.6), countdown(v.0.4.0), xfun(v.0.36), fastmap(v.1.1.0), showtextdb(v.3.0), withr(v.2.5.0), stringr(v.1.5.0), knitr(v.1.41), generics(v.0.1.3), vctrs(v.0.6.2), grid(v.4.2.2), tidyselect(v.1.2.0), glue(v.1.6.2), R6(v.2.5.1), fansi(v.1.0.3), readxl(v.1.4.3), rmarkdown(v.2.19), pander(v.0.6.5), whisker(v.0.4.1), farver(v.2.1.1), purrr(v.1.0.1), tidyr(v.1.2.1), magrittr(v.2.0.3), prismatic(v.1.1.1), ellipsis(v.0.3.2), scales(v.1.2.1), htmltools(v.0.5.4), showtext(v.0.9-5), zvplot(v.0.0.0.9000), colorspace(v.2.1-0), labeling(v.0.4.2), utf8(v.1.2.2), stringi(v.1.7.12) and munsell(v.0.5.0)

Go Figure! RSS Pre-Conference Workshop 2023 - Zak Varty